Knotty Alder Staining | How to Guide | Plastpro | Plastpro Inc
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Materials Needed:

  1. 1ZAR® Exterior Water Based Poly High Performance (Qt)
  2. 2ZAR® Stain (Qt)
  3. 3Mineral Spirits (4 Oz.)
  4. 4Cheese Cloths
  5. 5Two 2” foam brushes
  6. 6One 2½” synthetic bristle brush
  7. 7Two stir sticks
  8. 8One pair of latex gloves
  9. 9Door staining instructions
  10. 10Two skin samples
  11. 11Artist brush
  12. 12Brown or black paint marker

How-to 5 Step Guide: Staining Knots on a Plastpro Knotty Alder Door

Guide on Staining Fiberglass Doors

STEP 1: SURFACE PREPARATION (DO NOT SAND FIBERGLASS!)

  1. Lay door horizontally on saw horses or a table.

  2. Remove all hardware and mask off anything you don’t want stained, such as the glass insert.

  3. Wipe the door with mineral spirits to clean any dust or residue from the surface. Allow door surface to dry completely before applying stain.

*For best stain results, please make sure temperatures are between 50°F - 90°F, humidity below 85%, do not stain in direct sunlight, and do not stain or apply top coat when dew is present.

Step 2: Identify the Knots

  1. Look for the cracks and swirl marks on the doors.

  2. Identify how many knots you would like to accentuate.

NOTE: Before you apply stain to the door, please review all the options used to create the knots in Step 4. Option C will require you to fill in the cracks before applying stain to the door.

Step 3: Apply the Stain to the Door

FIRST COAT

  1. Starting at the center of the door, stain one to two panels at a time. Apply stain with a 2½”soft bristle brush, or a rag. Apply enough stain to fill the door grain. (Refer to the door staining diagram.)

  2. With a clean, lint-free cloth, softly wipe the surface until you reach your desired tone.
    TIP: When the rag becomes saturated with stain, re-fold to work with a less-saturated section. Be sure to use the same rag for the whole door.

  3. After all the stain is brushed evenly, you may add finishing touches by using a small 1” to 2” brush or cotton swabs.

SECOND COAT (if desired)

Let the stain dry thoroughly per the stain manufacturer’s recommendation before applying the second coat of stain. Temperature and conditions will affect dry time.

Step 4: Create the Knots (USING ONE OF THE THREE OPTIONS BELOW)

FOAM BRUSH OPTION A

  1. First, darken the cracks using the foam brush. Dip the foam brush gently in the stain, brush off the excess on the side of the can, and apply directly onto the crack. Darkening the crack creates contrast against the finish of the door and will help the door achieve the look of real wood.

  2. Use the bristle brush to create a circular shape around the crack.

  3. To create a lighter stain knot: Wait 10-15 minutes and gently wipe off any excess stain with the kit’s cloth.
    To create a darker stain knot: Wait for the current layer of stain to dry, and then apply more stain with the kit’s cloth. Dip the cloth gently in the stain, and apply thin layers in circular motions, following the swirl graining around the crack. Allow each layer to dry before applying a new layer. Repeat this process until you have reached your desired shade.

ARTIST BRUSH OPTION B

  1. Darken the cracks using an artist brush. Dip the artist brush gently in the stain, brush off the excess on the side of the can, and apply directly onto the crack. A brush with a finer tip will allow more precise strokes.

  2. Use the bristle brush to create a circular shape around the crack.

  3. To create a lighter stain knot: Wait 10-15 minutes and gently wipe off any excess stain with the kit’s cloth.
    To create a darker stain knot: Wait for the current layer of stain to dry, and then apply more stain with the kit’s cloth. Dip the cloth gently in the stain, and apply thin layers in circular motions, following the swirl graining around the crack. Allow each layer to dry before applying a new layer. Repeat this process until you have reached your desired shade.

PAINT MARKER OPTION C

TIP: With this method, you wlll have to fill in the cracks first with the paint marker, and then apply stain to the door.

  1. Use a brown paint marker on lighter finished doors (Morrocan Red, Champagne, Blue Moon, Mink) and black paint marker on darker finished doors (Mocha, Dak Chocolate Truffle, Black Caviarl) and fill in the cracks according to preference.

  2. Use the bristle brush to create a circular shape around the crack.

  3. To create a lighter stain knot: Wait 10-15 minutes and gently wipe off any excess stain with the kit’s cloth.
    To create a darker stain knot: Wait for the current layer of stain to dry, and then apply more stain with the kit’s cloth. Dip the cloth gently in the stain, and apply thin layers in circular motions, following the swirl graining around the crack. Allow each layer to dry before applying a new layer. Repeat this process until you have reached your desired shade.

Step 5: Protective Top Coat

Apply a polyurethane top coat with UV inhibitors like ZAR™ Exterior polyurethane, Wood Kote® Flagship UV, or Minwax® Fast Drying Polyurethane for exterior applications.

  1. After the stain has completely dried (48 hours), mix the top coat well and apply evenly, using a clean, dry 2” soft bristle brush or a 2” foam brush. Be sure to stop when the grain changes direction.

  2. Apply two or three coats of finish, allowing at least 2-4 hours of drying time between each application.

Normal Maintenance

Even a well-finished fiberglass door will be affected by exposure and weathering from the sun, moisture, and air pollutants.
It is considered normal maintenance to re-apply the topcoat approximately every two years.

*Staining instructions are for Oil-Based, Premium Quality Wood Stains, or similar products designed for use on a fiberglass surface. Please note the instructions indicated are specific to the Zar brand stain included in our stain kit. Please reference the stain manufacturer’s instructions before applying any stain.